SCINTILLATION LIGHT YIELD OF Ce-ACTIVATED LSO, LYSO, LuAP AND LuYAP

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SCINTILLATION LIGHT YIELD OFCe-ACTIVATED LSO,
LYSO, LuAP AND LuYAP
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AUTHORS Andrzej J. Wojtowicz and Winicjusz
DrozdowskiN. Copernicus University
(UMK)Research, characterization of scintillator
materialsJean-Luc Lefaucheur, Zbigniew Galazka
and Zhenhui GouPhotonic Materials Ltd (PML)RD
on LYSOCe, LuAPCe, LuYAPCePML manufactures
LYSO and is the only company supplying large LuAP
and LuYAP crystals on commercial scale
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CRYSTALS LSO (Lu2SiO5Ce, oxyorthosilicate)2x
2x10 pixels, grown by CTI Inc, provided bydr C.
Melcher, dr P. Lecoq, dr C. Kuntner, prof. S.
TavernierLYSO (Lu2(1-x)Y2x SiO5Ce,
oxyorthosilicate), LuAP (LuAlO3Ce, aluminum
perovskite), LuYAP (LuxY1-xAlO3Ce, x0.7,
aluminum perovskite)2x2x10 pixels and 5x5x1
plates grown by PML
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SCINTILLATION LIGHT YIELDand ENERGY
SPECTRA Incoming gamma particle may get
absorbed by giving up all its energy to a single
electron (photoelectron) get scattered away by a
single electron(Compton electron) and
escape Energy of (photo- or Compton) electron is
transformed into scintillation Scintillations
differ a plot showing number of scintillations
(y axis) vs amount of light in a single
scintillation(x axis) is called energy spectrum
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Energy spectrum, BGO, pixel 2x2x10mm, vertically
Hamamatsu R1104 950 V, Cs 137 (662 keV), spectr.
ampl. gain 3, note photopeak, Compton edge,
backscatter peak
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Energy spectrum LSO 1050 CTI 2x2x10 mm
pixel vertically Hamamatsu R2059 (1500 V) Na-22
(511 i 1274 keV) spectr. ampl. gain 3 Note two
photopeaks and two Compton edges, the third
developing peak (between 800 and 1000) and edge
(at 720)
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Light yield measurement standard method LSO 1050
CTI and two BGO 2x2x10 mm pixels,
vertically Hamamatsu R2059 (1500 V) Cs 137 (662
keV) and Na22 (511, 1274 keV)
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Energy spectraBGO old 2x2x10 vertically Hamamat
su R2059 (1500 V)Cs137 (662 keV) spectr. ampl.
gain variable Note photopeaks shift with gain
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Photopeak positions vs spectr. ampl. gain PP vs
G)BGO old 2x2x10 pixelR2059 1500 V, Cs 137
(662 keV)note offset y0
Photopeak position at 1 MeV12.0/0.662 18.1
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Energy spectraBGO new 2x2x10 vertically Hamamat
su R2059 (1500 V)Na 22 (511, 1274 keV) spectr.
ampl. gain variable Note photopeaks shift with
gain
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Photopeak positions vs spectr. ampl. gain(PP vs
G)BGO new 2x2x10 pixelR2059 1500 V Na22
(511, 1274 keV)note offset y0
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Energy spectraLSO 1050 2x2x10 vertically Hamamats
u R2059 (1500 V)Cs 137 (662 keV) spectr. ampl.
gain variable
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Photopeak positions (PP) vs spectr. ampl. gain
(G)(PP vs G)LSO 1050 2x2x10R2059 1500 VCs 137
(662 keV)
Photopeak position at 1 MeV 96.7/0.662 146.1
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STANDARD METHOD summary of LSO 1050
Does it work well?What if we change the voltage?
This cant be right! LY must be constant!
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Let us see if we can understand what is
wrong.The signal from the PMT should look like
this
S is a signal at PMT, V voltage, K number of
photoelectrons at photocathode, n number of PMT
stages, and a constant (assumed different in
each case)
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from these expressions for Ss it follows that
and now we see why the ratio of Ss for LSO and
BGO depends on V this is because alphas are
different. Now, does it make sense, can they
really be different? Different scintillators
produce different load on photocathode
distributed differently in time

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SLSO and SBGO vs PMT voltage
Photopeak position fitsLSO 1050 Y X9.39826
2.05489E-028 662 keV BGO oldYX9.053.31 BGO
new Y X9.16 1.89E-028, 511 and 1274 keV

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SUMMARY of results from fits

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SUMMARY of results from fits

No systematic dependence on V. Fits give good
averaged LY value from a number of spectra
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ENERGY SPECTRA and scintillation light yield
LYSO (PML)
3h energy spectrum of LYSO 2x2x10
verticallyR2059, 1500 V, Na 22the best pixel so
far Energy resolution12.2 (511 keV)7.3 (1274
keV)

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ENERGY SPECTRA and scintillation light yield
LYSO (PML)
3h energy spectrum of LYSO 2x2x10
horizontallyR2059, 1200 V, Na 22the best pixel
so far Energy resolution11.3 (511 keV)7.6
(1274 keV)6.9 (1785 keV) Note the third
peak The vertical/horizontal ratio 0.61, the
highest ever

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ENERGY SPECTRA and scintillation light yield
LYSO (PML)

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ENERGY SPECTRA and scintillation light yield
LYSO (PML)

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ENERGY SPECTRA and scintillation light yield
LuAP (PML)
LuAP plate, 5x5x1 (PML) R2059, 1500 V, spectr.
ampl. gain 3, Na22 note the third peak

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ENERGY SPECTRA and scintillation light yield
LuAP (PML)
LuAP plate, 5x5x1 (PML) R2059, 1500 V, spectr.
ampl. gain 3, Na22 note the third peak

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ENERGY SPECTRA and scintillation light yield
LuAP (PML)
LuAP plate, 5x5x1 (PML) R2059, 900 V, spectr.
ampl. gain 300, Na22 note the third peak

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ENERGY SPECTRA and scintillation light yield
LuAP (PML)
LuAP plate, 5x5x1 (PML) R2059, 900 V, spectr.
ampl. gain 300, Na22 note the third peak

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ENERGY SPECTRA and scintillation light yield
LuAP (PML)
LuAP plate, 5x5x1 (PML) R2059, 1500 and 900 V,
Na22

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ENERGY SPECTRA and scintillation light yield
LuYAP (PML)
LuYAP plate, 5x5x1 (PML) R2059, 1500 V, spectr.
ampl. gain 3, Na22

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SUMMARY We have developed a new method to
measure scintillation light yield of scintillator
materials The method, unlike the standard
method, requires that a number of spectra for
different amplifier gains and PMT voltages are
measured The method takes into account offset of
energy spectra and unexpected voltage dependence
and provides good undistorted values
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The method has been used to study a
representative set of LYSO, LuAP and LuYAP
crystals grown by PML The LYSO developed by PML
reached a mature stage the best LYSO pixel is by
50 brighter than a good LSO pixel 1050 LuYAP
and LuAP crystals developed by PML show LYs that
are comparable (LuAP slightly ahead) The
important source of loss of light must be some
unidentified absorption centers that quench
scintillation in longer samples